Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix a bunch of "sentence not on new line" warnings in section 9.

MFC after: 1 month

Fix panic on attaching to non-existent interface (introduced by r233937, pointed by hrs@)
Fix panic on tcpdump being attached to interface being removed (introduced by r233937, pointed by hrs@ and adrian@)
Protect most of bpf_setf() by BPF global lock

Add several forgotten assertions (thanks to adrian@)

Document current locking model inside bpf.c
Document EVENTHANDLER(9) usage inside BPF.

Approved by: kib(mentor)
Tested by: gnn
MFC in: 4 weeks

- Fix prototype of bpf_filter().
- Document what passing it a zero buflen argument means.

Use 'manual page' instead of 'man page' for consistency.

Approved by: re (hrs)

Fix prototype for bpf_mtap2().

MFC after: 3 days

Markup fixes.

Scheduled mdoc(7) sweep.

Remove trailing spaces.

Reviewed by: brueffer
MFC after: 3 days

Add a man page for the kernel part of bpf. I made some edits to the
man page after Orla, so the mistakes are probably mine. Leave a
note on the door welcoming the mdoc police.

Submitted by: Orla McGann <orly@cnri.dit.ie>